what happened

[reefnut]

woke up this morning to find my valentini puffer with a very swollen mouth,he also looks like hes had a good feeding which is weird because the lights had only been on for 1o mins.he will not eat and it looks as though his tongue is swollen to.he doesnt look like he'll make it.so what happened? did something bite him in the night maybe a worm or could it be a water quality issue.I test calcium.alk,ph,amonia no3,no4 never had issues with it.sg1.024 and temp76-78.what do you guys think?im at work and havent had a chance to test water this morning.